Clooney received the award during the annual gala for the Institute, which is housed at the USC Dornsife College of Letters, Arts and Sciences.

Jon Stewart hosted the event, which opened with an appearance from Sandra Bullock, who stars with Clooney in the new movie Gravity. Norah Jones provided the musical entertainment. Turner Network Television served as the presenting sponsor.

Held in New York this year, the gala brought nearly 800 people to the American Museum of Natural History in Central Park. Clad in cocktail attire, academics, university officials and celebrities mingled in the museum’s large facility to raise money for a worthy cause.The mood was both somber and upbeat. Bullock introduced a searing testimony from the Rwandan genocide, but also noted that good can prevail in the world. And while she teased Clooney by calling him a “child,” she also thanked him for his childlike optimism that helps propels his humanitarian efforts.

In presenting the Ambassador for Humanity Award, Spielberg told the audience that Clooney deserved to be recognized for his tireless efforts to raise awareness to the plight of recent victims of genocide, including the mass killings in Darfur and elsewhere.

Spielberg noted that Clooney helped found the Not on Our Watch project, which seeks to prevent future atrocities. And his humanitarian efforts reach into other areas as well: He has also helped organize aid to victims of the 2010 Haitian earthquake and has been named a United Nations Messenger of Peace.

“George is the best kind of humanitarian,” Spielberg said. “He is a humble humanitarian.”

Spielberg said that Clooney isn’t looking for publicity when he tackles issues.

“He said something that is at the core of the USC Shoah Foundation,” Spielberg recalled. “He said, ‘Wouldn’t it be great if even without the spotlight, we were steadfast to help those in need?’ ”

He noted that Clooney stands behind his words with action.

“He not only supports, but also participates with boots on the ground,” Spielberg said. “He’s been shot at literally.”

Spielberg also talked about the need to fight against the lull that can occur when time passes.

“We’ve all heard the expression, ‘Time heals all wounds,’ ” he said. “I don’t like that expression. Time can sometimes let us forget that some people are slower to heal, they have sadness, still grieve and still have incredible loss.”

In accepting the award, Clooney said the USC Shoah Foundation is doing an important job in keeping global atrocities in the spotlight.

“Our job is to try to make it hard for the bad guys to deny they are doing what they’re doing,” Clooney said. “It’s really hard for bad things to happen in bright light.”.

While Clooney said the work the Shoah Foundation does is important, he said the world would be a better place if such organizations didn’t need to exist.

“It would be nice to make what we’re doing here obsolete,” he said.

USC President C. L. Max Nikias promised that the university would remain committed to the institute’s goal of adding new voices to its Visual History Archive and reaching out to people who can learn from its message. In thanking Clooney for his humanitarian efforts, he called him a “brother to stand against genocide.”

“[The testimonies] teach us that when vigilance fades, intolerance follows,” Nikias said. “My university will forever safeguard the precious, life-affirming testimonies of the Visual History Archive. We shall not fail. We shall not falter. We shall not forget.”

USC Shoah Foundation Executive Director Stephen Smith thanked the audience for its continued support. Smith, who this week was named the inaugural holder of the UNESCO Chair on Genocide Education, talked about how the institute has grown since Spielberg founded it after making the Academy Award-winning film Schindler’s List.

“Through the USC Shoah Foundation, the legacy of your film, Steven, you gave the chance for many lights to shine in full color.

“It’s your vision,” he added. “We are changing the world through testimony — through the power of the human story.”

Robert Katz, the event’s co-chair and chair of the institute’s Board of Councilors, told the crowd that this year’s gala was the most successful yet, bringing in nearly $3.7 million to the institute.

Among the people he introduced to the audience were neuroscientist Mary Helen Immordino-Yang from USC’s Brain and Creativity Institute, based at USC Dornsife, who said testimony can change the way people think; Freddy Mutanguha, a survivor of the Rwandan genocide, who spoke about losing his entire family; and New York teacher Liz Bommarito, who has seen her students excel academically while learning new ways to change the world through the institute’s free online school program IWitness.

Between the seriousness of the institute’s mission and his job as a comedian, Stewart said he struggled to find the proper tone for the evening. But he had the audience laughing while poking gentle fun at himself, Spielberg and Clooney.

“I’m honored to be here because, as a Jew, there’s nothing more sacred than the Upper West Side,” he said. “I told my mother I was going to a Shoah benefit with Spielberg. She said, ‘You’re only four blocks from Zabar’s. She has a list, too.”

But he also looked to the future and urged the audience to keep fighting the good fight.

“Please stay on the journey,” he said.

Spielberg started the USC Foundation in 1994 after completing Schindler’s List. His vision was to create an archive of testimony of survivors and other witnesses of the Holocaust. Since then, the foundation has collected nearly 52,000 testimonies from 57 countries in 37 languages that encompass a wide range of experiences.

After finding a permanent home at USC in 2006, the institute continues to expand, with 65 testimonies from the Rwandan genocide recently added to its Visual History Archive. A full range of testimonies are available to scholars, researchers and students. It is also the base for a number of educational programs aimed at children.